1. Field of the Invention
The present invention relates to a power output apparatus and a movable body with a power output apparatus mounted thereon.
2. Description of the Prior Art
A type of proposed power output apparatus has a constant speed control system that keeps the revolving speed of a drive shaft at a preset level (for example, JAPANESE PATENT LAID-OPEN GAZETTE No. 1-114547). A cruise control system mounted on an automobile, for example, automatically regulates, in response to a driver's setting of a desired vehicle speed, the throttle opening of an engine without any operation of an accelerator pedal, so as to keep the vehicle speed at a preset level.
In a non-working status of the cruise control system, the driver can operate an accelerator pedal and a brake pedal according to the conditions of a road or another driving path (that is, the loading applied to wheels), for example, a slope, to regulate the vehicle speed to a desired level. The cruise control system in a working status, on the other hand, may not sufficiently handle the situation of a relatively large load applied to an axle, for example, during a drive on a steep slope, and fail to keep the vehicle speed at the preset level. While the vehicle runs on a relatively steep downslope, the vehicle speed may significantly exceed the preset level due to an insufficient braking force output to the axle.